Car manufacturers are. They probably get a bulk discount on relatively cheap data plans. It was enough for GM to keep OnStar running until Verizon got rid of supporting all 2G and 3G service in the USA.
Do we know how long they are paying for that connection?
I can’t imagine that’s cheap. Is a 2016 car internet connected without my notice? How do you confirm?
No, but the Wikipedia article seems to indicate that OnStar has the ability to store GPS and phone contact information even if you aren’t subscribed.
Also, I can’t imagine that buying several millions of data connections would be that expensive, especially if all that those connections are doing are sending out a ping of reports once a month.